Distillation device and process



Nbv. 14, 1944.- w. A. DARRAH 2,362,889

DISTILLATION DEVICE AND PROCESS Filed Feb. 5, 1942 [nwmtor Patented Nov. 14, 1944 UNITED STATES PATENT OFFICE DISTILLATION DEVICE AND PROCESS William Austin Dari-ah, Chicago, 111.

Application February 5, 1942, Serial No. 429,624

Claims.

This invention relates to equipment for separating various types of materials by distillation. It is particularly applicable for the separation of different fractions of oils or similar materials. One application is the separation from a vegetable or animal oil or fat, such ingredients as vitamins or the separation of saturated from unsaturated oils, thus removing for example a drying oil fractionfrom an oil which has only poor drying qualities.

As an example of the application of this process it is possible to extract from the oil of the babassu nut a component which has definite drying ability and may therefore be used for a paint vehicle or varnish. The remainder of the fat may be used for food or other purposes.

This invention has for some of its objects the provision of a device and a process for rapidly and economically causing separations of different fractions of materials one group of which ar represented by natural fats and oils.

This invention provides equipment and means for substantially accelerating processes heretofore possible only at relatively slow rates.

The increase in the rate of separation which this device permits naturally reduces the size and cost of the installation and the cost of carrying out the operation, thus making commercially possible fractions and separations which have hitherto been more or less laboratory curiosities or at least possible only on very expensive products.

The device permits control and increases the uniformity of the product and the sharpness of the separation.

Other objects of this invention will be apparent from a study of the disclosures and claims herein.

One of the special features of my invention is the provision of means for electrically accelerating and controlling the flow of molecules from the material being treated.

Referring to the drawing, Figure 1 shows in diagram a form of my device. It is to be understood that this drawing is diagrammatic and obvious changes in form and construction fall within the scope of my invention.

In the drawing, Figure 1 represents a housing or container provided with an inlet opening 2 closed by stopper or closure member 3 and providing access for a supply of liquid 4 from container 5. A control valve 6 regulates the rate of flow of liquid through inlet 1 and onto receiving electrode 8.

Receiving electrode 8 enters container I through opening 9 and embodies in its construction acirculating member l0 through which a heat regulating medium is circulating. The arrows indicate an optional direction of flow.

The liquid subjected to distillation passes from container 5 through control valve 6 into supply means 1 and flows from the open bottom end of supply duct 1 onto front over serrated member 8. As the liquid passes from the upper end of 8 downward under the action of gravity it of course flows over the outer edge of each of the stair like serrations or points so that the liquid is caused to pass successsively over a series of relatively sharp points. This results in successively exposing all portions of the liquid to the treatment resulting from the discharge from the multiple of sharp edges of stair like serrations of 8.

H indicates a control which may be thermostatic and regulates the flow of heat control medium through member l0 thus in turn controlling the temperature of electrode 8 and the relatively thin film of liquid from container 4 which is passing over it.

For purposes of the diagram it may be indicated that the medium controlling the temperature of electrode 8 enters through duct l3 and leaves from duct l2. I4 indicates a cork or stopper member to hermetically seal the opening 9.

Electrode 8 may be preferably made of material having appreciable conductivity but still of high resistance. A material such as carborundum, metalized porous porcelain, or similar material may be used to advantage. I have found that by rubbing graphite as for example the lead of a lead pencil over a rough and porous porcelain that suiiicient conductivity for the purpose at hand may be obtained.

It Will be noted that the liquid which passes from container 4 and flows over the greatly extended surface of electrode 8 in a thin film ultimately falls into receptacle I5 in the bottom of container l and then is removed through duct l6 by pum p ll which is driven by motor l8. This material is discharged into duct l9 to suitable storage tanks or holding devices.

Optional for cleaning out the equipment a valve 20 is placed at the bottom of receptacle l5 and leads through duct 2| and valve 22 into container 23 which serves as a storage tank or for other purposes.

Referring again to container I an opening 24 is provided for a receiving electrode 25. This electrode passes through stopper member 26 which forms a hermetical seal with container 1. Receiving electrode member 25 is provided with two ducts 26 and 21 through which a temperature controlling medium is circulated. This medium is indicated as being controlled by thermostatic device 28.

In the case of both electrodes the medium for controlling temperatures may be either gaseous or liquid. As a typical example in the case of electrode 8 which is normally required to operate at a higher temperature than electrode warm water or even diphenyl oxide may be circulated. In the case of electrode 25 which is normally operated at a lower temperature than electrode 8 air or cooling water may be circulated.

A gauge or indicator which may be of any conventional type as for example a mercury column is shown by 29 and indicates the pressure in chamber I which is ordinarily considerably below atmospheric pressure.

30 indicates a vacuum pump driven by a motor 3i and exhausting from chamber I through duct 32 and trap 33.

A receptacle 34 in chamber I located below electrode 25 serves to collect the condensate on electrode 25 which falls off of the bottom of it and collects in 34. This may be exhausted through pump member 35 driven by motor 36 and connected by duct 31 with the lower portion of chamber I. Valve 38 may be used to control the flow from receptacle 34. The discharge from pump 35 may be delivered through duct 39 to storage tanks or containers in the usual way.

For cleaning and maintenance receptacle 34 is continued by means of duct 40 which is provided with valve M and extension 42. A valve 43 is provided at the lower portion of extension 42 and serves to contro1 the flow of liquid out of 42 into container 44.

Valves 45 and 46 in members 2| and 42 respectively are designed to open up their respective ducts to permit air to flow in and allow the liquid in trap 33 to flow out into the respective containers.

This device may be operated in a great many ways. One simple method consists in reducing the pressure within container I until the proper working degree of vacuum is obtained. This is accomplished by means of pump 30 driven by motor 3|.

Trap 33 prevents flooding pump 30 with liquid which might be drawn out of container I.

Having established a working vacuum, valve 6 is opened sufficiently to allow the controlled flow of liquid from container 4 onto electrode 8. Electrode 8 is preferably so shaped as to expose a large surface to the liquid entering from container 4. This of course is the liquid which is to be subjected to the fractions or distillation.

At or before the instant the liquid is allowed to flow on electrode 8 the temperature controlling medium is circulated through coil I0, electrically and mechanically connected to electrode 8 as indicated. The flow of heat control medium such as for example hot water or steam is passed continuously through I0 and controlled by the thermostat to maintain a constant temperature.

The thermostatic element may be set so that the temperature of 8 will be constant and at the predetermined value. A typical operating condition for this temperature might be between 150 and 250 F. There is of course no reason why this temperature may not be varied as required by the nature of the material being distilled.

At the time that the temperature is adjusted in electrode 8 a similar adjustment is made in electrode 25 by means of the temperature controlling medium passing therethrough. This adjustment should be such that the vapor pressure of the materials leaving electrode 8 will be such as to maintain a substantial portion of the distillate as a liquid which will flow down the walls of electrode 25 and collect in receptacle 34.

When the equipment is in operating condition a difference of potential is applied between electrode 8 and electrode 25 as indicated diagrammatically in the drawing. If conducting liquids are used in the tubular members l0 and 25 for controlling temperature these liquids may serve as a conducting medium. Another alternate form would be to make the members In and 25 from conducting metal tubing, preferably of course some material which is air tight and not corroded or attacked by the materials being treated. In many cases copper, lead, tin or even steel tube may be used for this purpose.

It is of course well known that when a potential difference is applied between a point and a plate (or a conducting surface free from points) that a discharge tends to pass from the point to the plate. This condition is generally recognized and takes place independently of whether the point is positive or negative. The discharge occurs with greater facilities in some cases when the point is negative and in others when the point is positive. The facility of discharge is affected by such factors as pressure, temperature, nature of the gases, nature of the electrode, nature of th discharge, etc. The fact however that the discharge takes place with greater facility from a sharp point than from a relatively flat surface is of importance in causing a discharge to pass in the direction shown in the arrow on Figure 1 from the stair like serrations 8 to the relatively smooth surface of receiving electrode 25. On inspecting the construction shown in Figure 1 it will be evident that the liquid being subjected to treatment will successively pass over the edges of the serrations 8 from top to bottom and at each of the sharp edges will be subjected to the fiow of current from the stair-dike member 8 to the relatively smooth member 25. This discharge will carr molecules of vapor in a directional discharge which is not always dependent on which portion of the equipment is positive and which portion is negative but is dependent on the physical contour of the structure.

In applying a potential difference between the two electrodes I prefer in most cases to make electrode 8 positive and electrode 25 negative as indicated on the drawing.

The potentials used will of course depend on the physical dimensions of the unit, the separation between the electrodes, the degree of completeness with which air or vapor is withdrawn from container I, the nature of the material being treated and numerous other factors.

I have obtained very remarkable results with voltages ranging in some cases as low as 1000 volts. In other cases of considerable spacing and low pressure I have, to advantage, used Voltages from 70,000 to 100,000 volts.

Obviously the matter of voltages are merely dimensional factors and I do not wish to be restricted to any particular range as long as substantial voltage is available,

The application of a difference of potential between electrodes 8 and I serve to cause a flow of electrons and charged particles across the intervening gap. This condition causes several interesting results. The temperature at the surface of electrode 8 is increased, the relative vapor pressure of the material to be fractionated and flowing over electrode 8 is raised, and strong currents are created tending to cause the molecules of vapor to travel with the electron discharged.

I prefer to expose a relatively large surface on both of the electrodes but I prefer in general to have the electrode carrying the material to be treated, provided with a large number of points for facilitating discharges. On the other hand I prefer in general that electrode 25 which is intended to receive the flow of material should have as few points as possible and relatively large surfaces with large radii at points of curvature.

In certain cases I may find it advisable to insert electrostatic shields which I would apply in accordance with well-known physical laws.

It will be apparent that the density of the electrical discharge will be greatest at the points and a minimum at the cavities of electrode 25.

I It is therefore desirable to have the material being treated flow more or less continuously over the edges from top to bottom.

It is my belief that as the liquid flows over the edges and passes through the area of relatively concentrated discharge that the more volatile molecules will be turned from the body of the liquid and will travel toward the cooler collecting electrode of opposite polarity. It is my belief that the removal of the fraction from the material being treated occurs principally from the surface layer and therefore I prefer to have substantial agitation or mixing in order to continuously expose a new surface layer to the action.

This is one of my objects in providing the serrated or stairlike structure indicated in the diagram on electrode 8. I do not wish to restrict my invention to any particular contour providing the shape offers an opportunity for a more or less turbulent flow of the liquid being treated and also the opportunity to separate it to concentrated points of electrical discharge.

As the liquid collects in chamber I below electrode 8 and in chamber 34 below electrode it may be continuously pumped out of the system by pumps l I and 35 respectively. These pumps therefore serve as means of continuously withdrawing the accumulated results of the process.

In case small batches are to be treated the results of the process may be allowed to accumulate in the ducts 2| and 42 respectively and withdrawn from these ducts by closing valves 20 and 4| respectively, opening valves 22 and 43 respectively, and then opening valves 45 and 46 respectively so that the air pressure above columns will equal that of the atmosphere.

The design shown on Figure 1 may well be constructed of glass or quartz but I do not wish to confine myself to this material as the process that I have described permits continuous com.. mercial operation on a large scale and by applying proper insulating means, which are obvious to those skilled in the arts, container 1 may be constructed of any air tight material, very much as mercury arc rectifiers are now built.

In a similar manner the various tubes, pipes, ducts'etc. may be constructed of the obvious engineering materials best suited for the purpose, whether they be quartz, glass, synthetic resins or metal.

I have obtained very consistent results with direct current applied in the manner indicated.

I have found however that alternating current may be employed and providing the frequency of alternation is not so great that electrons discharged from one electrode do not reach the other, increases in frequency alternations appear to increase the activity of the device, probably because of the greater density of electrons per unit of cross section of space between the two electrodes.

In view of my experience with both alternating and direct currents I do not wish my invention to be limited to either condition.

My experience would indicate that the lower the molecular weight of the fraction removed, the greater is the advantage of alternating current. I have also found that alternating current requires a very greatly increased amount of cooling for electrode 25 and in most cases a very definite reduction in the heat input required from the heat control medium in electrode 8 and removed from electrode 25 will be somewhat proportional to the amount of material treated and the amount of fraction recovered. Of course these factors will be substantially modified by the radiation and other losses of heat.

The device which I have described may be used to advantage in fractionating many oils and fats, some proteins and other ingredients.

The device may be usedas a deodorizer in many cases, removing volatile fractions of materials strongly marked with foreign odors. In the case of vegetable oils not ordinarily classed as drying oils, this device makes possible the separation of definite amounts of drying oils. The treatment of castor oil, oiticia nut oil, babassu nut oil, palm oil, soya bean oil and others offer attractive commercial possibilities by the separation of definite fractions of drying oils from oils which are otherwise non-drying.

Furthermore a separation of mixed oils based on the size or length of the molecular chain is feasible with a device of this kind.

The treatment of chaulmoogra oil by this 4 method appears to make feasible the preparation of concentration of certain elements having decided medicinal purposes.

In operating my device I prefer in most cases to utilize a pressure within the container which is so low that the gas content will offer very little obstruction to the travel of molecules from the surface of the material being fractionated to the condensing medium. Because of the electrical field, I am able to operate under pressures and conditions which are much more favorable than those possible without the electrical field and I do not wish to be limited to one set of conditions only.

In operating my device the liquid to be treated is fed into the container from a source which is preferably held at a constant temperature.

The liquid flows over the serrated electrode which is maintained at a constant temperature thus insuring that the liquid is at the optimum temperature at all times.

A constant temperature is preferably maintained in the receiving electrode and the electric field is preferably maintained at a constant average value.

Of course the pressure within the unit is maintained constant.

I wish to point out the importance of maintaining conditions constant and at optimum value particularly when dealing with a continuous operation of commercial magnitude for which this equipment is designed.

In many cases I prefer to operate my process and device at pressures so low that the distillation will take place under conditions which are normally covered by the term molecular distillation. I wish it to be understood that my invention may be used under any conditions which fall within the scope of the claims appended hereto.

Having now fully described my invention, what I claim as new and desire to secure by Letters Patent in the United States is:

1. ,An apparatus for distillation consisting of a container, an electrode arranged to receive the material to be distilled, and arranged to permit said material to be distilled to flow over a series of sharp edges on said receiving electrode, a feeding means for delivering said material to be distilled to said electrode, another electrode arranged to receive the distillate recovered from said material to be distilled, a source of heat for said first electrode, means for removing heat from the second electrode, means for maintaining an electrical potential difference between said electrodes, and means for removing the distillate and the undistilled residue from'said container, said potential being applied so as to carry a surface layer of said distillate from the hot electrode to the cold electrode.

2. An apparatus for distillation consisting of a container, means for exhausting gas from said container, an electrode arranged to receive the material to be distilled, said electrode being provided with a series of edges so arrangedthat the material to be distilled travels successively over said edges and is to be subjected to an electric charge passing from said edges, a feeding means for delivering the said material to be distilled to said electrode, means for supplying heat to said electrode, another electrode arranged to receive the distillate, means for cooling said second electrode, and means for maintaining an electrical potential difference between said electrodes, said potential being applied so as to carry a surface layer of said distillate from the hot electrode to the cold electrode.

3. The process of continuous distillation which consists in continuously delivering a portion of liquid to be distilled, causing said liquid to travel by turbulent flow while exposed to a direct current electrical discharge, arranged to remove molecules from the surface of said liquid, and carry them to the cooler electrode, supplying heat continuously to said liquid during said treatment, and cooling said distillate continuously thus condensing the distillate thus removed.

4. The process of continuous distillationwhich' consists in continuously delivering a portion of liquid to be distilled, causing said liquid to travel by turbulent flow while exposed to a direct current electrical discharge, arranged to remove molecules from the surface of said liquid and carry them to the cooler electrode, continuously supplying heat to said liquid during said treatment, and continuously condensing the distillate thus removed, said operations being carried out at a pressure substantially below atmospheric.

5. The process of accelerating molecular dis-1 tillation by causing a flow of molecules to be torn from the surface of the flowing electrode and travel under the acceleration of a direct current electrical field through an evacuated space from an area of smaller radius of curvature, from a warm portion of liquid being distilled to an area of larger radius of curvature on a colder zone of distillate.

WILLIAM A. DARRAI-I. 

